Today there exists a vast number of towers, such as cellular telephone towers, railroad communication tower utilizing microwave, radio and satellite communications, and tilt-down towers, being erected across the country. Each tower includes a foundation embedded within the ground which prevents the tower for toppling over.
In the past, these foundations have been constructed by merely digging a hole in the ground and filling the hole with concrete to which the upright towers is anchored. This has been costly in that it requires that mixed concrete in fluid form be transported to each site, requires a curing time to pass before the next step of the process can be complete, thereby slowing the construction process and increasing costs, and requires a time or inspection delay between construction events which can cause days of delays to occur.
More recently, foundations have been made of a series of precast concrete components. The precast concrete components include large slabs with holes therethrough through which guide rods extend that coupled the slabs together. A problem with these slabs has been that the guide rods tend to move slightly or vibrate with the passage of nearby trains or other vehicles or due to environmental forces upon the tower such as wind and rain. This movement can cause the guide rods to chip or wear against the hole. Additionally, the bolts threaded onto the top's of the guide rods and against the slab may also wear upon the concrete surface, thereby causing a loosening of the bolt on the guide rod and against the concrete slab.
Another problem associated with precast tower foundations is that they include a large central passageway through the crown slab that does not always align with a space within the lower slabs. As such, electrical conduits associated with the equipment mounted to the tower coupled to the foundation are not always easily passed through the crown slab or are compressed between the foundation slabs.
Lastly, another problem associated with these precast tower foundations is that in some foundations the middle slabs are designed to include multiple legs which extend radially from a center of the foundation, typically foundations include four such legs. These slabs are often referred to as spiders. Because these slabs include multiple legs, the slabs have been formed by interlocking two separate blocks together at their center to form an X-shape in the horizontal plane, as shown in U.S. Pat. No. 5,231,808, which is incorporated herein by reference.
Accordingly, it is seen that a precast tower foundation crown slab that overcomes or alleviates the just described problems is needed. It is to the provision of such therefore that the present invention is primarily directed.